1. Field of Invention
The present invention relates to a method for controlling two GSM subscriber identification modules, and more particularly to a method for a GSM/CDMA dual-mode mobile phone to control two GSM subscriber identification modules.
2. Related Art
Currently, many specifications and standards are developed for wireless telecommunications. Common wireless telecommunications systems include global system for mobile communication (GSM), code division multiple access (CDMA), and personal handy-phone system (PHS). To cater users' requirements for a mobile phone capable of switching between different specification and standard systems, the mobile phone manufacturers have developed dual-mode mobile phones, for example, mobile phones with both GSM and CDMA systems.
FIG. 1 shows architecture of a GSM/CDMA dual-mode system of the prior art. Referring to FIG. 1, regarding the operating manner of this architecture, a GSM control module 110 may control a GSM subscriber identification module 130 that is electrically connected to a subscriber identification module (SIM) card. In addition, the GSM control module 110 may control a CDMA subscriber identification module 140 through a CDMA control module 120. The GSM control module 110 uses a GSM application layer 111 to provide a control command to a GSM device driver layer 113 through a GSM protocol stack 112. The GSM device driver layer 113 then outputs the control command to a CDMA device driver layer 123 of the CDMA control module 120 through a universal asynchronous receiver/transmitter (UART) standard. Then, the control command is transmitted to a CDMA application layer 121 of the CDMA control module 120 through a CDMA protocol stack/UIM protocol 122.
The CDMA application layer 121 further determines whether the control command is valid. If the control command is determined to be valid, the CDMA application layer 121 transmits the control command to the CDMA device driver layer 123 through the media of the CDMA protocol stack/UIM protocol 122 and the CDMA device driver layer 123 read the raw data of the CDMA subscriber identification module 140. The CDMA subscriber identification module 140 is electrically coupled to a user identity module (UIM) card. Then, the raw data of the CDMA subscriber identification module 140 is returned to the CDMA application layer 121 through the UIM protocol of the CDMA control module 120 in response to the control command.
Finally, the CDMA application layer 121 invokes the CDMA device driver layer 123 again to transmit the raw data to the GSM device driver layer 113 through the UART standard, and returns the raw data to the GSM application layer 111 through the GSM protocol stack 112. The GSM application layer 111 processes the returned raw data.
However, the prior art has the following unavoidable disadvantage. The GSM/CDMA dual-mode mobile phone is not adapted for a user having two GSM subscriber identification modules, that is, a user having two SIM cards. To use the dual-mode function of the GSM/CDMA dual-mode mobile phone, the user is required have a SIM card and a UIM card respectively corresponding to a GSM number and a CDMA number. To use two SIM cards corresponding to two GSM numbers, the user must buy another mobile phone for inserting the SIM card. Therefore, the mobile phone cannot meet the requirements of a user who does not have a CDMA number but has two GSM numbers. Therefore, the practicability of the GSM/CDMA dual-mode mobile phone is reduced.